Deformation Characteristics Research Articles

Utilisation of waste rock backfill materials in deep gobs for mitigating mining-induced water inrush risks: compression deformation and seepage characteristics

ABSTRACT In deep backfilling coal mines, granular waste rocks face complex stress and water environments after being backfilled in the goaf. To characterize the compression deformation and seepage of granular waste rock backfill materials in the deep goaf, a fluid-structure interaction (FSI) test system for granular waste rocks was developed. Influences of overburden stress on deformation and seepage characteristics of granular waste rocks were investigated. The research shows that the high overburden stress in deep underground coal mines can continuously change the structure of granular waste rocks. In the process of increasing overburden stress from 15 to 22.5 MPa, the porosity of granular waste rocks decreases rapidly and the permeability reduces fast accordingly. After the axial pressure exceeds 22.5 MPa, the porosity and permeability of granular waste rocks both tend to be stable. In the seepage process of confined groundwater under single overburden stress, the increase in water pressure can improve the porosity and permeability of granular waste rocks. Small waste rocks in samples play the leading role, they can achieve a waterproof state under relatively low overburden stress. The backfilling method that combines large and small particles can be considered, which can achieve rapid water proofing at a low cost.

High-resolution geological studies of seismogenic structures

Strong earthquakes rank among the most devastating natural disasters, with the potential to inflict catastrophic damage on communities and critical infrastructure worldwide. The structural geological and geophysical study of seismogenic features remains a cornerstone of earthquake research, providing essential insights into the dynamic processes driving these powerful events. High-resolution investigations in geomorphology, stratigraphy, and structural geology allow for a detailed understanding of the spatial and temporal characteristics of seismic deformations, encompassing co-seismic, post-seismic, and inter-seismic stages, potentially spanning multiple earthquake cycles. The integration of cutting-edge techniques—such as high-resolution data from Light Detection and Ranging (LiDAR), Structure from Motion (SfM), geophysical surveys, drilling, and frictional laboratory experiments—coupled with precise dating methods, enables quantitative analysis at high spatial resolutions across diverse temporal ranges, from years to millions of years. Recent advancements in frictional experimental techniques and numerical modeling have also significantly refined our understanding of deformation processes within seismogenic structures. This special issue compiles research on tectonic activities related to seismogenic structures from varied global tectonic setting, with a focus on leveraging high-resolution spatial data and sophisticated dating techniques. The contributions aim to deepen our understanding of the dynamics underlying strong earthquakes and improve our capacity for seismic hazard assessment.

XCT-assisted micromechanical modeling of the effect of pores on the plastic deformation and mechanical characteristics of PBF-LB/M-produced copper alloys

XCT-assisted micromechanical modeling of the effect of pores on the plastic deformation and mechanical characteristics of PBF-LB/M-produced copper alloys

Strength and deformation characteristics of cement-stabilized Fe-rich fine iron ore tailings

Strength and deformation characteristics of cement-stabilized Fe-rich fine iron ore tailings

Development of in-situ anisotropic deformation characteristics detection equipment for loess hole

Development of in-situ anisotropic deformation characteristics detection equipment for loess hole

Energy evolution and deformation features of re-loading creep failure in yellow sandstone after cyclic water intrusion

Energy evolution and deformation features of re-loading creep failure in yellow sandstone after cyclic water intrusion

Tilting deformation analysis and instability prediction of arch-locked-segment landslides induced by rainfall

The failure of locked-segment landslides is associated with the destruction of locked segments that exhibit an energy accumulation effect. Thus, understanding their failure mode and instability mechanism for landslide hazard prevention and control is critical. In this paper, multiple instruments, such as tilt sensors, pore water pressure gauges, moisture sensors, matrix suction sensors, resistance strain gauges, miniature earth pressure sensors, a three-dimensional (3D) laser scanner, and a camera, were used to conduct the physical model tests on the rainfall-induced arch locked-segment landslide to analyze the resulting tilting deformation and evolution mechanism. The results indicate that the tilting deformation characteristics in the locked segment are consistent with the variation in its strain, stress, hydrodynamic responses, and slope morphology, suggesting that tilting deformation can serve as a novel monitoring approach for landslide instability. Further, the tangent angle method and the tilting rate reciprocal method can be utilized to predict the landslide instability based on the landslide tilting deformation curve. The effectiveness of this method is validated in the Huangzangsi dam area, which provides theoretical foundations for understanding the catastrophic mechanism and instability prediction of arch-locked-segment landslides.

Study on the Mechanical Characteristics and Degradation Response of Unloading Rocks Surrounding Tunnels in Cold Regions

The excavation of the rock mass at the tunnel entrance in regions characterized by high altitudes and elevated stress levels results in the direct exposure of the surrounding rock to atmospheric conditions. This surrounding rock is subjected to the compounded effects of excavation-induced unloading damage and freeze–thaw erosion, which contribute to the degradation of its mechanical properties. Such deterioration has a negative impact on production and construction operations. Following tunnel excavation, the lateral stress exerted by the surrounding rock at the tunnel face is reduced, leading to a predominance of uniaxial compressive stress. As a result, the failure mode and mechanical behavior of the rock exhibit characteristics similar to those observed in uniaxial loading tests conducted in controlled laboratory environments. This study conducts laboratory-based uniaxial loading and unloading tests, as well as freeze–thaw tests, to examine the strength, deformation characteristics, and fracture attributes of unloading sandstone subjected to freeze–thaw erosion. A damage deterioration model for unloading sandstone under uniaxial conditions is developed, and the patterns of damage response are further analyzed through the identification of compaction points and the definition of damage response points. The results indicate that (1) as the degree of freeze–thaw erosion increases, the failure threshold of the sandstone significantly decreases, with the residual rock fragments on the fracture surface transitioning from hard and sharp to soft and sandy; (2) freeze–thaw erosion has a pronounced negative impact on the cohesion of the sandstone, while the reduction in the internal friction angle is relatively moderate; and (3) the strain induced by damage following three, six, and nine freeze–thaw cycles exhibits a gradual decline and appears to reach a state of stabilization when compared to conditions without freeze–thaw exposure. Investigating the mechanical properties and deterioration mechanisms of the rock in this specific context is crucial for establishing a theoretical foundation to assess the stability of the tunnel’s surrounding rock and determine the necessary support measures.

Failure modes and interaction mechanisms of tunnel under active landslide conditions

The construction of tunnels can easily trigger the reactivation of old landslide bodies, posing a threat to the transportation safety. In this study, using methods such as engineering geological investigation, slope deformation monitoring, deep displacement monitoring, and numerical simulation, the interaction between landslides and tunnels was investigated from the perspective of landslide deformation and failure characteristics. The Walibie Tunnel (WLBT) of Shangri-La to Lijiang (XL) expressway was taken as an example. The results showed that there were two unstable slopes developed in the upper part of the tunnel, with the new active landslides. Shallow and deep creeping deformation zones also exist within the landslide area. Combining the position of the deformation zones of the unstable slopes and the actual tunnel damage observed, it was determined that the failure mode of the tunnel was longitudinal tensile fracture in the traction section-tunnel. Numerical simulation and field investigation revealed the mechanism of interaction between the WLBT and landslides: the traction section of the tunnel passed through the unstable slope parallelly, and during the continuous opening and expansion process at the rear edge of the unstable slope, a significant tensile force was exerted on the tunnel, resulting in initial tensile fracture damage.

Large-Eddy Simulation of Droplet Deformation and Fragmentation Under Shock Wave Impact

This study employs the large-eddy simulation (LES) approach, together with the hybrid volume of fluid—discrete phase model, to examine the deformation and breakup of a water droplet impacted by a traveling shock wave. The research investigates the influence of Weber number on transient deformation and breakup characteristics. Particular focus is given to the detailed analysis of sub-droplet-size distributions, which are frequently overlooked in existing studies, providing a novel insight into droplet fragmentation dynamics. The predicted deformation and breakup patterns of droplets in the shear breakup regime align well with experimental data, validating the computational approach. Notably, LES is able to reproduce the underlying physical mechanisms, highlighting the significant role of recirculation zones and the progression of Kelvin–Helmholtz instabilities in droplet breakup. Additionally, it is shown that higher Mach numbers significantly amplify both cross-stream and streamwise deformations, leading to earlier breakup at higher airflow pressures. Increasing the Weber number from 205 to 7000 results in 25% reduction in the average size of the sub-droplets, indicating the strong influence of aerodynamic forces on droplet fragmentation. This comprehensive analysis, while aligning with experimental observations, also provides new insights into the complex dynamics of droplet breakup under post-shock conditions, highlighting the robustness and applicability of the proposed hybrid Eulerian–Lagrangian formulation for such advanced applications in fluid engineering.

Using monitoring and simulation to analyze the failure characteristics of multizone landslides controlled by faults: a case study

Slopes influenced by multiple faults are prone to large-scale landslides triggered by multi-regional failures. Understanding the failure process and sequence is essential for the sustainable development of mining operations. This paper presents a method combining InSAR monitoring and numerical simulation to analyze the failure processes of slopes affected by multiple faults. Using the 298–710 m bench in the central area of the eastern slope of the Nanfen open-pit mine as a case study, the multidimensional small baseline subset (MSBAS) technique of InSAR was employed to calculate the vertical and horizontal deformation time series in the study area, enabling an analysis of the deformation characteristics of multizone bedding sliding. Subsequently, a numerical simulation was performed to replicate the three-dimensional evolution of the multizone failure. The simulation results aligned well with field surveys and InSAR monitoring data. Furthermore, the failure sequence analysis identified critical trigger zones within the region. The findings demonstrate that the proposed method effectively identifies the critical areas and movement sequence of multi-regional failures. In this paper, the faults disrupted the connectivity between slopes, acting as the initial trigger for entire landslide. The first failure occurred in a critical area, creating space for further sliding in other regions and reducing lateral constraints in neighboring areas, eventually leading to significant deformations. Therefore, by using this method to identify potential critical areas before landslides occur, targeted mitigation measures can be implemented to reduce the risk of such events.

Structural and Dynamical Response of Lipid Bilayers to Solvation of an Amphiphilic Anesthetic.

The structural response of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC)/water bilayers to addition and subsequent solvation of a small amphiphilic molecule - an anesthetic benzyl alcohol - was studied by means of solid-state NMR (2H NMR, 31P NMR) spectroscopy and low-angle X-ray diffraction. The sites of binding of this solute molecule within the bilayer were determined - the solute was shown to partition between several sites in the bilayer and the equilibrium was shown to be dynamic and dependent on the level of hydration and temperature. At the same time, it was shown that solubilization of benzyl alcohol reached a solubility limit and was terminated when the ordering profile of DMPC hydrocarbon chains adopted finite limiting values throughout the whole chain. Such findings were made probably for the first time for any lipid bilayer system and possibly have more general implications for dissolution of other small-molecule amphiphilic solutes in lipid bilayer systems other than DMPC. The limit to the hydrocarbon chain profile is probably a more general property and corresponds to the balance of intrabilayer and interbilayer forces established in combination with the elastic properties of the bilayer system that still consists of one single phase just before the solute forms an excess phase. It is not necessary to quantify the contribution of each individual intrabilayer and interbilayer force acting within such a bilayer system. A model of the dependence of surface density of lipid chains on the chain segment order parameter was also developed - an empirical mathematical model based on experimental data was derived and it was proposed to represent a relationship between intrinsic bilayer forces and bilayer deformation characteristics and might be proven to be of more general significance in the future.

Dynamic modeling and guidance analysis of a ferromagnetic continuum robot with geometric discretization and base linear motion

Abstract With the advancement of robotics in medicine in recent years, diverse and promising applications for ferromagnetic continuum robots (FCRs) have been introduced. These robots utilize an electromagnetic actuation system for movement and control, which leads to reduced tissue damage, significantly shorter surgery durations, and improved patient recovery times. Recent research in FCR modeling highlights the critical challenge of developing a dynamic model to assess system behavior in real-time, crucial for maximizing benefits in medical applications. In this paper, the geometric discretization method and Lagrange’s principle are used to derive the dynamic equations of a FCR under the influence of an external magnetic field. This approach enables the examination of the system’s behavior at any given moment, providing a suitable foundation for designing various controllers based on the model. Given the electromagnetic system used in steering the FCRs, an analysis of the magnetic field in both ideal and real conditions is conducted to enhance reliability for medical applications. Simulation results indicate that the robots deform in a direction different from the magnetic field direction, demonstrating non-planar deformation characteristics. Furthermore, comparison with experimental data demonstrates that the theoretical framework accurately predicts the robot’s deformation, with calculation errors less than 5%.

Study on the mechanics performance and deformation characteristics of polypropylene fiber-reinforced solid waste-based fill material

Study on the mechanics performance and deformation characteristics of polypropylene fiber-reinforced solid waste-based fill material

Seismic Behaviors of Historic Timber Buildings Considering the Looseness of Mortise-Tenon Connections

ABSTRACT Due to the effects of the long-term loads, earthquakes, as well as aging and decay of the wood, existing historic timber buildings (HTBs) are inevitably damaged, especially by mortise–tenon loosening. Therefore, this paper aimed to investigate the seismic behaviors of HTBs considering the looseness of mortise–tenon connections. Shaking table tests were conducted on a 1/3.52 scale model of an intact HTB made by the Engineering Code of the Qing Dynasty to simulate seismic loads and study the seismic response of HTBs. The deformation characteristics, failure modes, and dynamic response of the test model were all studied. Furthermore, the modal and dynamic response analyses of all finite element models (FEMs) were used to investigate the influence of looseness on seismic behaviors of HTBs. The results show that with a larger damaged degree than 13.3%, the inter-story drift ratio (IDR) θ of the damaged model with looseness mortise–tenon connections resulted from earthquakes, is more than the IDR limit of 1/30 under an 8-degree rare earthquake, indicating that the HTBs must be strengthened and retrofitted immediately.

Local characterization of collagen architecture and mechanical properties of tissue engineered atherosclerotic plaque cap analogs.

Many cardiovascular events are triggered by fibrous cap rupture of an atherosclerotic plaque in arteries. However, cap rupture, including the impact of the cap's structural components, is poorly understood. To obtain better mechanistic insights in a biologically and mechanically controlled environment, we previously developed a tissue-engineered fibrous cap model. In the current study, we characterized the (local) structural and mechanical properties of these tissue-engineered cap analogs. Twenty-four collagenous cap analogs were cultured. The analogs were imaged with multiphoton microscopy with second-harmonic generation to obtain local collagen fiber orientation and dispersion. Then, the analogs were mechanically tested under uniaxial tensile loading until failure, and the local deformation (strain) and failure characteristics were analyzed. Our results demonstrated that the tissue-engineered analogs mimic the dominant (circumferential) fiber direction of human plaques. The analogs also exhibited a physiological strain stiffening response, similar to human fibrous plaque caps. Ruptures in the analogs initiated in and propagated towards local high-strain regions. The local strain values at the rupture sites were similar to the ones reported for carotid human fibrous plaque tissue. Finally, the study revealed that the rupture propagation path in the analogs followed the local fiber direction. STATEMENT OF SIGNIFICANCE: Many cardiovascular events are triggered by mechanical rupture of atherosclerotic plaque caps. Yet, cap rupture mechanics is poorly understood. This is mainly due to the scarcity of plaques for high-throughput testing and the structural complexity of plaques. To overcome this, we previously developed tissue-engineered cap analogs. The current study characterizes (local) structural and mechanical properties of these cap analogs. Our findings show that: (1) cap analogs closely mimic human fibrous caps, including fiber orientation and strain stiffening responses; (2) structural and mechanical properties of cap analogs are associated, which provides critical information for understanding plaque rupture; and (3) cap ruptures commonly start in and propagate towards high-strain areas, indicating the potential use of strain measurements for cap rupture risk assessment.

Study on Torsional Shear Deformation Characteristics of Segment Joints Under the Torque Induced by Tunnel Boring Machine Construction

Study on Torsional Shear Deformation Characteristics of Segment Joints Under the Torque Induced by Tunnel Boring Machine Construction

Research on the coupling control mechanism of yielding-bolt-grouting in deep water-enriched roadway and its engineering application

Groundwater seepage can easily cause large deformation and fracture instability of the surrounding rock in deep roadways, and the coupling support of “yield-bolt-grouting” can effectively control the occurrence of such accidents. This paper takes the specific engineering geological conditions of deep water-enriched roadway as the research background, revealing the coupling control mechanism of yield-bolt-grouting. The mechanical characteristics of the yielding tube were determined using lab analysis, and an investigation was conducted for the support control mechanism of high-strength yielding bolts. The control mechanism of grouting reinforcement is summarized, and a comprehensive coupling control technology system of “yield-bolt-grouting” is proposed based on the rheological large deformation characteristics of the surrounding rock of deep water-enriched roadway, with high-strength yielding grouting anchor rods and high-strength yielding grouting anchor cables as the core. The on-site monitoring results indicate that this technology effectively controls the deformation of the surrounding rock. The research results provide new ideas and technical approaches for controlling the surrounding rock of deep water-enriched roadways.

Bond Performance of GFRP Bars in Glass and Basalt Fiber-Reinforced Geopolymer Concrete Under Hinged Beam Tests

In recent years, researchers have focused on the usability of fiber-reinforced polymer (FRP) bars due to their lightweight, corrosion-resistant, and eco-friendly characteristics. Geopolymers, as low-carbon alternatives to traditional binders, aim to reduce CO2 emissions in concrete production. The bond strength between FRP bars and concrete is critical for the load-bearing capacity and deformation characteristics of reinforced elements. The objectives of this work are to investigate the bond performance of GFRP bars in chopped glass and basalt fiber-added geopolymer concrete using hinged beam tests. Since the hinged beam test accurately represents the behavior of real bending elements, this test method was selected as a main bonding test. Initially, three geopolymer mixtures with Ms modulus values of 1.2, 1.3, and 1.4 were prepared and tested. The mixture with a modulus of 1.2 Ms, achieving a compressive strength of 56.53 MPa, a flexural strength of 3.54 MPa, and a flow diameter of 57 cm, was chosen for beam production due to its optimal workability and strength. After mechanical and workability tests, SEM analysis was performed to evaluate its internal structure. For evaluating the bond performance of GFRP bars, 12 geopolymer beam specimens were prepared, incorporating varying fiber types (chopped glass fiber or basalt fiber) and embedment lengths (5 Ø or 20 Ø). Hinged beam tests revealed that the bond strengths of glass and basalt fiber-added mixtures were up to 49% and 37% higher than that of the control geopolymer concrete, respectively. It was concluded that incorporating fibers positively influenced the bond between geopolymer concrete and GFRP bars, with glass fibers proving more effective than basalt fibers. These findings enhance the understanding of bond mechanisms between GFRP bars and geopolymer concrete, emphasizing their potential for sustainable and durable construction in both industrial and scientific applications.

Analysis and optimization of threaded shear energy absorbing components of collision resistance hydraulic support columns

Conventional energy-absorbing components have limitations in terms of performance and functionality, including significant variability in reaction forces, inherent instability, and inadequate energy absorption capabilities. This paper presents a threaded shear-type energy-absorbing component designed for anti-impact hydraulic support columns, specifically for ZQL advancing support roadway hydraulic supports. The component operates based on the principle of threaded shear energy absorption. Its key structural parameters—such as thread shape, outer diameter, and pitch—are optimized using single-factor and response surface experimental design methods. Shear simulations are performed to analyze the deformation and force-displacement characteristics across various structural configurations. The impact of different thread parameters on energy absorption performance is evaluated, with quasistatic shear tests and simulations validating the results. The optimized design enhances energy absorption efficiency and provides a foundation for future research on integrating these components into hydraulic support systems to improve overall performance.